A pericentric inversion of chromosome 4 in pigs

Abstract

Summary -The main French porcine artificial insemination centre recently decided to carry out a systematic chromosomal evaluation of the animals used for pure-breeding purposes. This practice has allowed the identification of a new pericentric inversion affecting chromosome 4, in four Large White boars originating from four different herds. The cytogenetic evaluation by means of the GTG-banding technique revealed an inversion of the pericentric part of the chromosome, after double breaks, the first one in the 4q2.3 pale band of the long arm, and the second one in the upper border of the 4pl.4 dark band of the short arm. The chromosomal rearrangement could be described, according to the standard nomenclature, as 38,XY,inv(4)(p14q23). This interpretation has been confirmed

Cytogenetic and molecular characterization of�eight new reciprocal translocations in the pig species. Estimation of their incidence in French populations

“…Reciprocal translocations generally lead to an important decrease of the reproductive performance of carrier animals or of their mates (the estimated average effect on prolificacy was −40% [8]). The information obtained for 3 out of the 8 translocations described here, although not very accurate, confirms this long known fact [13], and helps to justify the control programmes carried out.…”

“…The total number of reciprocal translocations reported for the pig species in 1998 was 68 [4,8]. Since that time, 11 new reciprocal translocations have been published: rcp(8;14)(p21;q25) and rcp(7;13)(q13;q46) [7], rcp(2;9;14)(q23;q22;q25) and rcp(7;15)(q24;q26) [20], rcp(13;17)(q41;q11) and rcp(2;14)(q13;q27) [9], rcp(8;10)(p11;q13) [22], rcp(1;7)(q17;q26), rcp(4;12)(p13;q13) and rcp(1;6)(q17;q35) [25], and a 1q+/15q− translocation [18].…”

“…However, a more thorough analysis revealed that the chromosome considered as a supernumerary chromosome 10 was in fact a rearranged chromosome 5 lacking its short arms (breakpoint in 5p11). The corresponding fragment (5p11 → 5pter) appeared as a p-terminal band on chromosome der (8). The reciprocity of the chromosomal exchange could not be proved using banding techniques only, due to the very small size of the chromosome fragment translocated from chromosome 8 to chromosome 5.…”

“…Control programmes were initiated in several European countries as early as the beginning of the 1970's. Based on karyotypic analyses of hypoprolific boars detected using national herd management databases [19], they led to the discovery of numerous chromosomal rearrangements, mainly reciprocal translocations [4,8]. The continuous improvement of chromosome banding techniques [27] made it possible, during the last decade, to identify and characterize new rearrangements modifying very slightly the morphology and/or the banding profile of the chromosomes.…”

Estimation of the proportion of genetically unbalanced spermatozoa in the semen of boars carrying chromosomal rearrangements using FISH on sperm nuclei

“…The economical consequences of such abnormalities can be very important if the animals which carry the rearrangements have a high number of mates, as is generally the case for reproducers used in artificial insemination centres [30]. These economical considerations result in the establishment of systematic control programs of young purebred animal candidates for reproduction in several selected porcine populations [9,11]. The analyses carried out have allowed the discovery of various chromosomal rearrangements carried by young animals controlled before reproduction, including reciprocal translocations, peri-and paracentric inversions, as well as trisomy mosaics.…”